As I was searching for additional information about the installation and siting of the Howard Pass RAWS, I came across the following NPS report discussing the summer 2013 and winter 2012-2013 weather conditions in the Western Arctic Parklands.
http://www.nps.gov/akso/nature/documents/WEAR Summer 2013 Weather Summary.pdf
A note in the document provides the following interesting statement: "At Howard Pass (see cover photos), winter temperatures were as low as -48° F in February and wind gusts as high as 84 mph in January. The minimum wind chill for February was -101° F on February 21. The average wind chill for February was -39.5° F."
The Howard Pass statement is accompanied by a time series chart for winter 2012-2013, complete with wind chill measurements:
If these measurements are correct, then the all-time Alaska wind chill record may have been broken last year at Howard Pass, and the 2013 event may still stand as the existing record. Curiously, the RAWS data archive at the Western Regional Climate Center shows corrupted or missing temperature data from Howard Pass prior to late July 2013, so I wasn't able to find the data to match the chart shown above. The wind chill of -101F would correspond to the minimum temperature of -48F combined with a wind speed of 54 mph.
Brian points out that some of the temperature reports from other stations in northern Alaska on February 21, 2013 were low enough to make the Howard Pass wind chill at least plausible; Anaktuvuk Pass reported a high temperature of -38F and a low of -45F.
Rick will be able to answer the question of whether this data was thrown out for some reason, or if it might have been overlooked by NOAA at the time.
I wonder if there is an on-site data logger that stores observations in case of transmission problems. Since the temperature data is missing all day long on the 21st (and many other days too) but the NPS has charts for those days, perhaps the data is recoverable.
ReplyDeleteThe NPS RAWS have onsite data loggers and this is where the 2012-13 temp data comes from. So this was not available in real-time, but does show that high winds and very low temps are a feature of the Howard Pass area.
DeleteI'm troubled by the apparent rush to record the output from that RAWS as fact. While it's interesting to observe the new and unique in our environment, taking the data that station generated as a new wind chill point is begging several questions.
ReplyDeleteWhat's the typical accuracy of the equipment at the observed extremes of minimum temperatures and maximum airspeed? What are the allowable calibration tolerances, and how might they typically affect the range of accuracy?
Other recent output from the unit appears suspect, and now the anemometer output appears to have ceased. I could go on but it takes more than faith to accept a unique event as factual.
I'm not attempting to generate an argument here. If the NWS and NPS believe the record has been set, and the data accurate, then that's their business. But in my experience there's more to reality than a generated stream of data.
Gary
Gary,
DeleteThe NWS does take into account the factors you mentioned, and it was the NWS's collective professional opinion that the observation was valid. That is, of course, no guarantee.
Rick...please note my comment elsewhere relative to an estimate of the potential variability of the transmitted data...AKA some sort of confidence interval and any potential overlap with the prior record.
DeleteThe NWS made the call on one degree of alleged separation. That's repeatable accuracy required for interplanetary travel in my opinion.
And as I note above and without drifting into the fog of epistemology, if that's how the record keeping business is conducted so be it. My name's not on the report.
Gary
Gary,
ReplyDeleteI couldn't agree more. I've tried to be careful to use tentative language in describing the possible new record. Any "official" determination on this - presumably by a climate extremes committee - would have to take a careful look at the equipment specs, calibration, and error ranges; and we may never have any confidence in the truth of the matter.
Based on images elsewhere here, I believe this is the source of the anemometer: http://www.youngusa.com/products/1/ I don't know the source of the temp sensor.
ReplyDeleteIt would be beneficial to have specs and sourcing for their RAWS units' various sensors. I've searched but no luck so far. That's likely available from the NPS via their vendor files.
If you read the manuals for the Young mechanical wind sensors, you'll note the as-supplied manufacturing tolerances. You'll also not that they can supply NIST pre-calibrated units. And you'll also note the various calibration scenarios that apply to the compass settings, and to the sensor unit's bearings. In addition, regulated voltage appears to be a critical aspect to the unit operation.
Rick noted the typical standard for RAWS sensor height (~20'). These units are ~9'. Wind velocity is proportional height AGL according to what I've read, mainly due to increased friction losses from the surface, and the potential for upset of laminar air flow the lower the sensor. Same for the proximity to nearby vertical terrain.
The recent data stream includes odd sensor outputs (like snow depth), and now a lack of windspeed. A caution note (source?) has also been generated. Mechanical failure may have occurred.
Going forward, as you suggest Richard maybe experts in this stuff can convene and discuss the goals of weather records, and the acceptable tolerances of the measuring equipment. A timely examination of the site is critical.
As far as a potential record being declared via social and public media, well that's a matter for internal protocol. What's entertainment for some can reflect the lack of science for others.
Sorry to be such a critic, but the record will stand unless it's reviewed in light of the source.
Gary
Weather extremes capture the public's attention. As long as the data passes an initial rational check, disclaimers like 'possible', 'tentative', etc., add the necessary level of scientific uncertainty (CYA?) to proceed with public dissemination. From an information perspective the world is flat and speed matters. Information that is not communicated quickly is either discarded entirely or deemed less relevant. If an errata has to be issued later, the public will probably not notice it, but the science community will.
ReplyDeleteA few years back there was a possible U.S. record snowfall in Montague, NY, and a committee reviewed the findings and determined that the measurements were taken too frequently and therefore the measurement was not accepted ( http://goo.gl/1m0igw ). An initial wrong was righted in that instance. Same as with the Angoon record rainfall.
Gary, your insight into the terrain, local conditions, equipment, and atmospheric process are extremely impressive. If there is an opportunity to ground truth the report, I would hope that you are part of the team. I would also argue that blogs like this, and the comments, set the groundwork for future verification.
Possible events like this add to the lore of Alaska – a place where all too often anecdotes are used in lieu of actual data.
Hi Brian et al. I'm confident all will be revealed, after all this isn't analogous to the claims for Cold Fusion.
ReplyDeleteWas it recently cold and windy in Howard Pass? Yes. Are the data distribution characteristics, potential sensor errors, and confidence values at various levels known between the two "record" sensors? Maybe someday.
Yes in the end it'll soon be old news until some soul walks up to the RAWS station and has a look at what condition it and its sensors are in.
In the meantime the research of value I feel is in the reanalysis of conditions during the time of the potential record. Knowing something may have been unique, and then examining the factors that may have contributed to that event, can help elevate this from the realm of potentially Gray Science.
A record was called by a Federal Agency, and now I feel it's up to them to support that fact. I hope they succeed.
Gary
"What's entertainment for some can reflect the lack of science for others." Reminds me of the movie The Core. I died a little inside while watching that. It wasn't even good science fiction.
ReplyDeleteGary, do aircraft keep any standard weather data in their blackboxes outside a normal trip. This would take some work but there had to be airplanes flying somewhat near the pass - even at 30,000 ft. This data could be used as constraints on modeling and as a sanity check. Of course, having radar in that area would be better.
Hi Eric. I'd have to go looking for the potential data lines available from the range of airline flight data recorders. I assume they'd include flight path and relative atmospheric info, in addition to the typical aircraft parameters such as system and control surface conditions. Don't know right now.
DeleteRichard, Brian, and Rick are excellent analysts.The reanalysis presented so far is illuminating and educational for me, and I assume for other readers as well. Excellent products, and generally unavailable elsewhere in a contemporaneous fashion.
I need to stand down on this and let them, and others associated with the NPS and NWS agencies, do their work. No point is focusing their efforts away from the task of confirmation.
One thing I'd consider doing if it were my job would be to "reanalyze" the respective RAWS sensor outputs from the Howard Pass station. Recapture and subject them to a lab environment capable of duplicating the conditions (temp, humidity, wind velocity, ???) extant at the time of the reporting. Unless the sensors are now compromised, the quality of their output might offer insight into the accuracy of the previously recorded data. That's all above my pay grade, however.
Gary